Textile process and product



March 17, 1964 KENYON ETAL 3,124,860

TEXTILE PROCESS AND PRODUCT Filed June 23, 1960 mb W 7 08 M 0 W m MHF 6 0m M W By f/re/r afiome MM Z M United States Patent ()ffice 3,124,860 Patented Mar. 17, 1964 5,124,860 TEXTILE PROCESS AND PRUDUCT Robert S. Kenyon and William Frank Taylor, Mobile, Ala, assignors, by mesne assignments, to Courtaulds, Limited, London, England, a British company Filed June 23, 1960, Ser. No. 33,282 Claims. (Q1. 2876) This invention relates to a method for improving the properties of regenerated cellulose textile material and in particular to a method for avoiding raveling of certain specific types of woven, regenerated cellulose fabric.

Fabrics made from regenerated cellulosehave been known for over fifty years and have had wide public acceptance. Although in many respects such fabrics are equal or superior to those made from natural cellulosic fibers such as cotton, in other qualities they are not as satisfactory. One shortcoming relates to the tendency of regenerated cellulose woven fabrics to ravel. This characteristic makes it necessary to take special precautions in manufacturing garments from regenerated cellulose and this in turn increases the cost of such garments.

One particular difliculty arises in the manufacture of wash and wear garments. Such garments are intended to be wearable immediately after washing and drying; no ironing being necessary. To avoid searn puckering in such garments it is customary to use blind seams. In blind seams the edges of the fabric are customarily left free and with regenerated cellulose fabrics, raveling becomes a serious problem.

In recent years much attention has been given to a new type of regenerated cellulose fiber.

The new type of regenerated cellulose fiber can be made by spinning viscose having a relatively high degree of xanthation :60 to 80) into a zinc-free, low acid bath. Many processes of this type have been developed in recent years. One is described in United States patent to Tachikawa 2,732,279. In the Tachikawa process, unaged viscose is spun into a zinc-free bath containing less than 30 g./l. H 50, and less than 50 g./l. Glaubers salt at a temperature below about 30 C. and the fibers are then drawn, in the bath, at a progressively increasing speed until regeneration is complete. Regenerated cellulose fiber made from this and similar processes is also characterized in having a fine and stable microfibrillar structure. It will also usually have a minimum wet strength of 2.2 g./denier and a Wet elongation of less than 3.5% at a stress of 0.5 g./ denier. Such fibers are often referred to as polynosique fibers.

Fabrics made from polynosique fibers are superior in many respects to more conventional regenerated cellulose fabrics. However, they also have the drawback, common to other regenerated cellulose fabrics, of raveling very readily.

In accordance with the present invention this drawback is remedied, for fabric made from polynosique viscose rayon fibrous material, by treating said fabric with a swelling agent for the cellulose. In accordance with the invention it has been found that such treatment stabilizes the edges of the fabric, preventing raveling.

It may be pointed out that with cotton fabrics no great difiiculty with raveling is experienced, and swelling treatments such as mercerization, show no substantial effect in this direction. With normal regenerated cellulose, on the other hand, treatment with swelling agents causes breakdown of the fiber structure and gives a brittle, boardy and unrnerchantable product. Hence it was quite unexpected that with this particular class of regenerated cellulose fabric a known treatment, impractical to use with normal regenerated cellulose, would give a new and extremely valuable result.

The drawing is a schematic diagram of a system suitable for practicing the invention.

The invention may be practiced using an aqueous solution of virtually any conventional cellulose swelling agent. Sodium hydroxide is preferred, but other alkali metal hydroxides, e.g. potassium hydroxide, may be used as well as such materials as zinc chloride and sodium zinc-ate.

The concentration of swelling agent used will vary with the particular agent, with the temperature and time of treatment and to some extent with the construction of the fabric. In general the concentration may vary between 5% by weight and about by weight. When alkali metal hydroxides are used the concentration will normally be between 5% and say 40%. With sodium hydroxide, concentrations of 5% to say 20% are preferred.

The time of treatment will vary with concentration, time, and fabric construction. In general it will range from say 15 to 50 seconds.

Treating temperature will vary with the other treating conditions but will in general be between about 15 and about 40 C.

The process according to the invention is applicable to all types of woven fabric construction, denser constructions may require longer treating times than less dense constructions and this requirement may, in turn, affect the concentration and temperature. However, the proper adjustment of these variables is well within the skill of the art.

The treatment may be applied to fabrics made wholly of polynosique viscose rayon fibrous material, to fabrics in which the polynosique viscose rayon fibrous material is blended with other fibers, and to fabrics in which yarns or threads of polynosique viscose rayon fibrous material are used concurrently with yarns of other fibers. These fibers should preferably not be adversely affected by caustic or other swelling agents. Examples of suitable fibers include cotton, nylon, polyester (e.g. polyethylene terephthalate) acrylic, polyethylene and polypropylene fibers. The greatest advantages of the invention are obtained when the proportion of polynosiq-ue viscose rayon is at least 5 0% by weight.

Normal regenerated cellulose fiber can be blended with the polynosique viscose rayon fibrous material, but when the proportion exceeds about 15% by weight the product becomes objectionably boardy.

In carrying out the invention, any convenient manipulative technique may be used. Preferably the fabric is treated on a conventional mercerizing machine. A sirn plified version of such apparatus is shown schematically in the drawing.

Referring to the drawing, the cloth 1 is fed over a roller 2 into a bath 3 containing from 5 to 80% by weight of a cellulose swelling agent. It moves through the bath over rollers 4 and is thereby impregnated with the bath liquor. After removal from the bath, the fabric travels over rollers 5, 6, '7 and 8 to a stenter frame 9. In accordance with the normal operation of a stenter frame the edges of the fabric are grasped by a series of moving clips (not shown) and stretched in the direction of the filling, transverse to the direction of fabric movement. The fabric is sprayed with water from spray heads 10 and 11, which serve to remove most of the caustic. It then moves under roll 12, over roll 13 and down into water bath 14. It passes through the bath 14 under rolls 15 where any remaining swelling agent is removed. From the bath 14, the fabric moves over roll 16 and thence down into bath 17. Bath '17 is a sour bath, containing a weak acid, e.g. from 0.5 to 1.5% acetic acid. The fabric moves through the bath 17 under rolls 18, and is then taken out, passed Over rolls 19 and delivered to water bath 20. In bath 20 the fabric is rinsed to remove acid, passing under rolls 21. It is taken out over rolls 22 and dried in any convenient type of dryer, indicated at 23.

If desired, after being subjected to caustic treatment, the fabric may be Sanforized. This is not shown in the drawing.

In addition to preventing raveling, the process according to the invention imparts to polynosique viscose rayon fabric, properties similar to those imparted to cotton fabrics by conventional mercerization. The luster of the fabric is also heightened.

The invention will be further described by means of the following specific examples, which are given for purposes of illustration only, and are not to be taken as in any way limiting the invention beyond the scope of the appended claims.

EXAMPLE 1 Polynosique viscose rayon staple fiber was made by extruding a viscose containing cellulose, 3% NaOH and having a 7 number of about 70 into a spinning bath at 28 C. containing about 3% H SO about 5% Na SO and no ZnSO and stretching by about 100% while the filaments were still less than 50% regenerated. The resultant fiber (3 denier x 2") was processed into a gabardine fabric, warp 14/1, filling 15/1, greige width 40 A".

Two batches of the fabric, after desizing, washing and drying were subjected to caustic treatment in accordance with the invention. Batch A was treated with a solution containing 6% by weight NaOH at 85 F. Batch B was treated with 18% NaOH at 102 F. Total time of exposure to caustic was 25 seconds, in each case.

Whereas the fabric before treating raveled easily at the edges, after treatment A or B, even extensive handling produced no raveling. After laundering in a conventional washing machine (one pound load) batch A showed a warp shrinkage of about 10% which increased to about 12% after five cycles. An additional five cycles showed no change. Batch B showed a warp shrinkage of about 9% which did not change substantially over 10 wash cycles. Untreated fabric showed a warp shrinkage of about 15% after one wash cycle which increased to about 17.5% after 10 cycles.

Lengths of the fabric from both batch A and batch B were Sanforized in a conventional Sanforizing machine using a felt blanket and a compacting of 4.2%

The Sanforized samples were then laundered. Batch A samples showed a warp shrinkage of about 7% and batch B a shrinkage of about 5%. Both were substantially unchanged after 10 wash cycles.

After treatment according to the invention, the tensile strength of the material tended to be higher as shown by Table I below.

Table II 6% NaOH 18% NaOH Con- Drape Stiflness trol Not San- San- Not San- Sanforized forized forized forlzed (\Varp and Filling) ineheS 1 1. 36 1. G4 1. 58 1. 73 1. 65

EXAMPLE 2 The procedure of Example 1 was repeated except that the fiber was 1% denier x 1% staple and was made into a challis fabric, warp and filling 22/1, greige width 39% As with the gabardine of Example 1, very little handlin'g was suflicient to cause the challis to show the raveling characteristics of conventional rayon fabrics. After treatment with either 6% NaOH or 18% NaOH this characteristic was eliminated and the edges of the fabric showed a resistance to raveling similar to cotton fabric of like construction. This challis fabric, moreover, showed a substantial increase in wet crease recovery after treatment as indicated in Table III below.

When subjected to laundering, fabric treated with 6% NaOH showed a warp shrinkage of about 5% which increased to about 6% after 10 washing cycles. Fabric treated with 18% NaOH showed a warp shrinkage of about 3.5% which did not increase significantly after 10 wash cycles. Untreated fabric showed a warp shrinkage of 11%, increasing to 12% after 10 wash cycles.

With Sanforization, fabric treated with 6% NaOH showed about 1% warp shrinkage with an increase to about 1 /2 after 3 cycles and no further change through 10 cycles. Fabric treated with 18% NaOH showed no significant warp shrinkage over 10 cycles.

While initially the challis fabric treated according to the invention showed a slight loss in tensile strength over untreated fabric, after a series of five boil wash cycles (using the technique described in AATCC Tentative Test Method 91-1958 [IV]), the treated fabric was generally stronger than untreated :fabric. This is shown in Table Table I IV below.

Table I 6% NaOH 18% NaOH V Tensile Strength Con- 7 (lbs) trol N ts s T 0 0 anan I\ot San- San- 6 N 011 Y iorized torized Iorized iorized Tensile Strength Cona 18% LQOH (lbs.) trol Warp biOhsflcllt- ISan- NotSan- San- Dry 98.3 130.0 126.6 109.0 100.2 mud {0mm fouled Wet 52.0 67.3 66.8 49.8 53.3 ii 64 2 7 7 s 4 55 54 4 65 Warp:

ry '7 .7 Dry 26.9 44.6 45. Vet 39. 6 39. 5 46.1 26. 3 31- 5 Vet 19. 0 24. 4 26, 2 i

FiIliBg:

ry 33. 4 42. 0 33. 0 21. 5 19. 4 Wet 22. 7 25. 4 17. 2 13. 5 17. 6 Treatment according to the invention imparts a certain degree of stiffness to the fabric. However, this is not great enough to be objectionable and is nothing like the boardiness obtained when conventional textile grade rayon is mercerized. This is borne out by Table II below showing drape stifiness.

From a consideration of the foregoing specification it will be observed that the invention provides a simple and inexpensive Way for improving the properties of rayon fabrics, making use of newly discovered properties of a specific type of rayon. In particular the invention makes it possible to prevent raveling of a specific type of woven rayon fabric. Thus it is particularly useful in the manufacture of wash and wear garments from rayon.

We claim:

1. A method for imparting a high resistance to raveling to woven fabrics containing at least 50% polynosique viscose rayon fibrous material which comprises treating said fabrics; with a swelling agent for the cellulose equivalent to an aqueous solution containing between about 5 and about 20% by weight NaOH.

2. The method claimed in claim 1 wherein the swelling agent is an aqueous solution containing between about 5 and about 20 by weight NaOH.

3. The method claimed in claim 1 wherein the treatment is carried out at between about and about 40 C. for from about 15 to about 50 seconds.

4. A woven fabric made from polynosique 'viscous 5 rayon fibrous material, said fabric having been treated with a swelling agent for cellulose equivalent to an aqueous solution containing between about 5 and about 20% by weight N aOH.

5. A method for treating woven fabric at least of which consists of polynosique viscose rayon fibrous material, which comprises impregnating said fabric with an aqueous solution of a swelling agent for cellulose equivalent to an aqueous solution containing between about 5 and about 20% by weight NaOl-I, stretching the impregnated fabric, removing the solution of swelling agent from the fabric and drying the fabric.

References Cited in the file of this patent UNITED STATES PATENTS 1,989,101 Lilienfeld Jan. 29, 1935 2,497,519 Stevenson et a1. Feb. 14, 1950 2,732,279 Tachikawa Jan. 24, 1956 2,809,089 Phillips et al. Oct. 8, 1957 OTHER REFERENCES Review of Textile Progress, vol. 1, 1949, page 51; published by The Textile Institute, Manchester, England.

Moncrieff: Artificial Fibers, 2nd ed. (1954), page 64, John Wiley and Sons, Inc., New York. 

1. A METHOD FOR IMPARTING A HIGH RESISTANCE TO RAVELING TO WOVEN FABRICS CONTAINING AT LEAST 50% POLYNOSIQUE VISCOSE RAYON FIBROUS MATERIAL WHICH COMPRISES TREATING SAID FABRICS WITH A SWELLING AGENT FOR THE CELLULOSE EQUIVALENT TO AN AQUEOUS SOLUTION CONTAINING BETWEEN ABOUT 5 AND ABOUT 20% BY WEIGHT NAOH. 